1. Field of the Invention
The present invention relates generally to an apparatus for tightening chains placed on motor vehicle tires, and more particularly, to an apparatus especially adapted to provide an automatic chain-tightening effect as the chains are in service on the vehicle.
2. Description of the Prior Art
During ice or snow conditions, chains are often installed on motor vehicle tires to increase traction. A problem often associated with the chains is that they may have a lot of slack and may be quite loose after they are installed. Some devices are known in the prior art to increase chain tension. For example, U.S. Pat. No. 3,888,290 of Hess et al discloses a tire chain tightener that employs a special cam between adjacent chain links to shorten the effect length of the chain. With such a device, the tightness of the chain must be manually adjusted periodically to adjust for chain wear and tire wear. It would be desirable, however, if a chain tightening device were provided that automatically tightened the chain as the chain and tire wear.
U.S. Pat. No. 4,130,155 of Barnett et al discloses a self-tightening connector for tire chains. This device is installed between chain links for automatically tightening the chain as the tire on the vehicle turns. U.S. Pat. No. 4,142,808 of Muller et al and U.S. Pat. No. 4,306,602 of Nestlen disclose other chain tightening devices that are installed between adjacent chain links. A problem associated with chain tighteners that are installed between adjacent chain links is that extra weight is added to the chain at certain locations on the chain, and the weight distribution around the chain becomes uneven. And when the weight distribution around the chain is uneven, the wheel becomes out of balance. It would be desirable, therefore, if a chain tightening apparatus were provided which tightened the chain without creating an uneven weight distribution on the wheel causing the wheel to become out of balance.
It may be of interest that another type of chain tightener, that cannot ride on the wheel with the chains, uses a hydraulic chain spreader to tighten the chain.
A number of problems are specifically associated with motor vehicle chains that are loose. One such problem is chain roll which occurs when loose portions of the chain bunch up and create their own rolling action. Such rolling action can lead to gouging of the tires. Also, when the chains are too loose, they may fly up and do damage to fenders on the motor vehicle. In these respects, it would be desirable if a chain tightener were provided which prevented chain bunch up. Moreover, it would be desirable if a chain tightener prevented loose chains from causing tire gouging and fender damage.
Thus, while the foregoing body of prior art indicates it to be well known to use chain tighteners for motor vehicle tire chains, the prior art described above does not teach or suggest a device that automatically tightens the chain as the chain and tire wear and that does not create an uneven weight distribution on the tire and wheel causing the wheel to become out of balance. The prior art does not provide a chain tightener prevents chain bunch up. In addition, the prior art does not provide a chain tightener that prevents loose chains from causing tire gouging and fender damage. The foregoing disadvantages are overcome by the unique tire chain tightening apparatus of the present invention as will be made apparent from the following description thereof. Other advantages of the present invention over the prior art also will be rendered evident.